JP6012708B2 - Method and apparatus for determining a plurality of MIMO layers - Google Patents

Description

  The present invention relates generally to base stations, user equipment (UE), and methods thereof. More specifically, the present invention relates to wireless communication, particularly the function of the user device.

  In a typical cellular radio system, a plurality of radio terminals communicate with one or more core networks (CN) via a radio access network (RAN). The plurality of wireless terminals are known as mobile stations and / or user equipment units such as tablet computers and laptops having wireless functions such as smartphones, cellular phones, mobile terminations, and so on. For example, the mobile device may be a portable, pocket storage, portable, computer-mounted, or vehicle-mounted mobile device that communicates at least one of voice and data via a wireless access network.

  RAN is a geographical area divided into a plurality of cell areas managed by a radio base station (RBS) which is a base station (BS), for example a so-called Node B, evolved Node B (eNB) or base station (BTS). Cover. The term “base station” is used below when referring to any of the above examples. A cell is a geographical area where radio coverage is provided by radio base station equipment at a base station site. The plurality of base stations communicate with user equipment units within the range of the base station via an air interface that operates at a radio frequency.

  In some versions of the radio access network, especially in older versions, some base stations are typically connected to the radio network controller, for example by landline or microwave. Radio network controllers also sometimes function as base station controllers (BSCs) that monitor or direct various functions of the base stations connected to them. A radio network controller is typically connected to one or more core networks.

  Universal Mobile Telecommunication System (UMTS) is a third generation mobile communication system that evolved from Global System for Mobile Communications (GSM), based on wideband code division multiple access (WCDMA) access technology, It is intended to provide an improved mobile communication service. A Universal Terrestrial Radio Access Network (UTRAN) is essentially a radio access network that uses wideband code division multiple access for user equipment units. The Third Generation Partnership Project (3GPP) guarantees further evolution of UTRAN and GSM based on radio access network technology.

  Long Term Evolution (LTE) is a variation of 3GPP radio access technology in which radio base station nodes are connected directly to the core network rather than radio network controller nodes. In LTE, the function of a radio network controller node is generally performed by a radio base station node. As such, the LTE system radio access network has a substantially “flat” architecture that includes base station nodes without reporting to the radio network controller node. LTE was introduced into 3GPP in Release 8. Release 9 and Release 10 are more recent releases of LTE. For example, release 8 may be described as rel-8, release 8, LTE release 8, or 3GPP release 8. The terms “codeword”, “layer”, “precoding” and “beamforming” are specifically adapted for LTE to refer to signals and their processing. The term “codeword” refers to user data formatted for transmission. The term “layer” has the same meaning as stream. In multi-input multi-output (MIMO), at least two layers must be used. Up to 4 can be used. The number of layers is always less than or equal to the number of antennas. The term “precoding” modifies the layer signal before transmission. This may be done in diversity, beam steering, or spatial multiplexing. Beamforming modifies the transmitted signal to give the carrier with the best carrier level to interference / noise ratio (CINR) at the output of the channel.

  In LTE, hybrid automatic repeat request (HARQ) with incremental redundancy is used. HARQ is a technique that enables faster recovery from errors in a communication network by storing corrupted packets at the receiving device rather than discarding them. Even if the retransmitted packet results in an error, good packets are extracted from the combination of multiple corrupted packets. Instead of retransmitting the same part of the codeword, a different redundancy version is retransmitted that yields a surplus in chase combining. Ideally, the received soft version of all codewords is stored if a full buffer is available on the receiving side. However, the soft buffer size of the user device is limited due to the complexity and cost of the user device. For higher rate transmissions, if a larger codeword is transmitted from the transmitter, the user equipment limits the buffer space and cannot store the complete codeword. The base station may send code bits that cannot be stored to the user equipment, and worse, the user equipment will not know that they are other bits and will be confused with the pre-stored bits.

  FIG. 1 shows a simple complete codeword (complete codeword) and the number of soft bits that a user can store. FIG. 1 shows a decoded transport block and coded bits stored by a user equipment, ie, a soft buffer size. As shown in FIG. 1, the complete codeword includes systematic bits and parity bits, and the soft buffer size includes all of the systematic bits and a portion of the parity bits. Parity bits are bits that are added to a group of source bits to ensure that the resulting number of bits is odd or even. The base station and the user equipment will have the same understanding of the soft buffer size, after which the base station will not transmit code bits that the user equipment cannot store. Instead, those code bits stored by the user equipment are acquired and used for transmission (retransmission). This is shown in the circular buffer of FIG. The term “circular buffer” refers to an area of memory used to store incoming data. When the buffer is full, new data is written over the old data at the write start position of the buffer. Codewords, ie, systematic bits and parity bits are stored in a circular buffer. FIG. 2 shows the bits used for the first transmission and retransmission taken from the circular buffer. The size of the circular buffer matches the soft buffer size of the user device. The complete cycle in FIG. 2 corresponds to the soft buffer size and does not correspond to the entire codeword. In the first transmission, depending on the coding rate, only some or all systematic bits, or some or all systematic bits and part of the parity bits are transmitted. . In the retransmission, the starting position is changed and bits corresponding to other parts of the cycle, eg other points of the cyclic buffer, are transmitted.

  In LTE Release 8 with frequency division duplex (FDD), each user equipment has up to 8 HARQ processes per component carrier. Each HARQ includes up to two sub-processes that support dual codeword MIMO transmission. LTE Release 8 divides available soft buffers equal to the configured number of HARQ processes. Each of the divided soft buffers can be used to store the soft value of the received codeword. For dual codeword MIMO transmission, the split soft buffer is further divided equally to store the soft values of the two received codewords.

  In 3GPP, the arrangement of soft buffer sizes is defined as follows.

A circular buffer w _k for the r th encoded block is generated as follows.

Here, K _Π is a constant.

The circular buffer is given by the length K _w = 3K _Π .

The soft buffer size in the transport block by N _IR bits is shown, and the soft buffer size in the r-th code block by N _cb bits is shown. The size N _cb is obtained as follows. Here, C is the number of code blocks.

Here, N _soft is the total number of soft channel bits.
K _MIMO is 2 if the user equipment is configured to receive the physical downlink common channel (PDSCH) based on transmission mode 3, 4 or 8, and 1 otherwise.
M _{DL_HARQ} is the maximum number of DL HARQ processes.
M _limit is a constant equal to 8.

  A soft buffer (SB) arrangement for the single codeword transmission mode is shown in FIG. FIG. 3 shows eight arranged soft buffers, SB0 indicates a first soft buffer for the first codeword, SB1 indicates a second soft buffer for the second codeword, and SB2 indicates A third soft buffer for a third codeword is shown. FIG. 3 shows the arrangement of soft buffers in LTE release 8 when the physical downlink common channel (PDSCH) transmission mode is other than modes 3, 4 or 8. It can also be seen that there is a reserved buffer for each codeword.

  The soft buffer arrangement for the dual codeword transmission model is shown in FIG. FIG. 4 shows 16 arranged soft buffers, SB0a shows the first buffer for the first codeword, SB0b shows the second buffer for the second codeword, and SB1a shows the third buffer SB1b indicates a fourth buffer for the fourth codeword. SB1b indicates a fourth buffer for the fourth codeword. Soft buffers apply to codewords. Codeword is the term used for the coded bits associated with a transport block. FIG. 4 shows a soft buffer arrangement in LTE release 8 when the PDSCH transmission mode is 3, 4 or 8. The transmission mode will be described in detail below.

  The buffer reserved for each codeword is only half of the previous operation case. The soft buffer limitation problem is particularly acute in double codeword MIMO transmission operations. This restriction reduces the effectiveness of soft combining the gain gained from incremental redundancy retransmissions.

<Carrier aggregation>
LTE Release 8 supports bandwidths up to 20 megahertz (MHz). However, in order to meet the requirements of International Mobile Communications Advanced (IMT-Advanced), 3GPP started operation from LTE Release 10. Part of LTE Release 10 is to support bandwidths greater than 20 MHz. An important requirement in LTE Release 10 is to ensure past compatibility with LTE Release 8, including spectrum compatibility. As a result, LTE Release 10 carriers wider than 20 MHz may appear as fewer LTE carriers to LTE Release 8 user equipment. Each such carrier may be referred to as a component carrier or cell. In the early stages of LTE release 10 deployment, it is expected that there will be fewer user devices that support LTE release 10 compared to many LTE legacy user devices. Therefore, it is desirable to ensure effective use of wide carriers by legacy user equipment. That is, it is possible that legacy user equipment may implement carriers that can be scheduled in the majority of LTE Release 10 carrier bandwidth. One way to achieve would be to use carrier aggregation.

  Carrier aggregation implies that a user equipment that supports LTE Release 10 may receive multiple component carriers that have the same structure or at least in part with LTE Release 8 carriers. FIG. 5 shows carrier aggregation. The x-axis in FIG. 5 shows the spectral width used for the five component carriers, and the y-axis shows the energy per frequency unit.

<Soft buffer operation in carrier aggregation>
In LTE, each component carrier operates with a set of HARQ processes. Since the total soft buffer memory needs to be shared by a plurality of component carriers, the soft buffer size per component carrier is the number of component carriers and the number of MIMO transmission modes for each component carrier. The available soft buffer size in each codeword that may vary according to also depends on how the soft buffer is divided and how all code words are arranged.

<LTE-supported multi-antenna>
Multi-antenna functionality is already included in LTE Release 8 and is important to enable high data rates, improved coverage and performance. Multi-antennas for transmission and reception can be used in different ways. Diversity techniques are used to improve link robustness. Beamforming techniques can be used to improve coverage. Spatial multiplexing provides a means to increase the spatial efficiency of a link and improves overall system performance if properly designed. The peak rate is substantially increased using spatial multiplexing, ideally increased in proportion to the minimum number of transmit and receive antennas on the link, the signal to noise ratio (SNR) is sufficiently high, and channel conditions are beneficial. There are provided. Real gains are high channel dependent and they require high SNR and beneficial interference conditions for the associated link, but can be substantially improved if the SNR is high enough. An example is a low system load scenario or when the user equipment is located close to the cell center.

  The LTE Release 8 downlink supports single user MIMO (SU-MIMO) spatial multiplexing up to 5 layers via a codebook based on precoding. Further, transmit diversity mode is supported on LTE Release 8 downlink, as well as beamforming with single layer transmission. In LTE Release 9, the high downlink transmission mode includes a beamforming function that has been extended to also support dual layer transmission, and multi-user MIMO (MU-MIMO) that has been proposed to transmit different layers to different users. ) And have been introduced. The uplink multi-antenna supported in LTE Release 8/9 limits the antenna selection of user equipment operating in all UE categories. The UE category is described in detail below.

  The LTE Release 8 user apparatus assumes the number of layers based on the minimum number supported by the base station and the minimum number supported by the user apparatus. The user equipment determines the number of layers supported by the base station by blindly detecting the number of cell-specific reference signal (CRS) antenna ports transmitted by the base station, or in case of handover (HO) Determines the number of layers supported by the base station by receiving information on the number of antenna ports supported by the target cell in the HO command.

Multi-antenna transmission is an important feature in LTE Release 8. LTE supports the following eight transmission modes (TM):
Mode 1: Single antenna port Mode 2: Transmit diversity Mode 3: Open loop spatial multiplexing Mode 4: Closed loop spatial multiplexing Mode 5: MU-MIMO
Mode 6: closed loop spatial multiplexing, single layer mode 7: single antenna port, user equipment specific reference signal Mode 8: single or dual layer transmission LTE advanced with user equipment specific reference signal, ie LTE release 10 , Mode 9 is included in addition to modes 1-8. Mode 9 is a multi-layer transmission mode that supports closed loop SU-MIMO up to rank 8 and high MU-MIMO support.

<UE category signaling>
User equipment is categorized by so-called UE categories or user equipment categories with different UE classes that define overall performance or user equipment performance. Hereinafter, the user equipment category is referred to as a UE category. The UE category needs to ensure that the base station can communicate correctly with the user equipment. By informing the base station of the UE category, it is possible to determine the performance of the user equipment and communicate accordingly.

  Since the UE category defines the overall performance and the performance of the user equipment, the base station can communicate using the process functions of the base user equipment. Thus, the base station will not communicate beyond the capabilities of the user equipment. Different values of buffer size are associated with each UE category.

  In LTE Release 8/9, there are five UE categories 1-5, and LTE Release 10 has three more categories 6-8.

  The LTE Release 10 UE category definition is built on the principles used in LTE Release 8/9, where the number of UE categories is limited to avoid fragmentation of user equipment implementation variables in the market. The LTE Release 10 UE category is defined in terms of peak rate units ranging from 10, 50, 100, 150, 300 Mbps to about 3 Gbps in the downlink. Realization of different peak rates is possible within the UE category. For example, categories 6 and 7 could either support two MIMO layers with 40 MHz carrier aggregation or support four MIMO layers with a single carrier at 20 MHz. There is. The two configurations support up to 300 Mbps. The LTE Release 8/9 UE category is reused, for example, to support a set of two component carriers up to 10 MHz bandwidth per Category 3 user equipment. It is expected that additional UE categories may be defined in the future. LTE Release 10 supports a high-end UE category that synthesizes a set of 5 component carriers at 20 MHz for every 8 MIMO layers, supporting a total peak data rate for 3 Gbps for LTE Advanced. Table 1 below shows the UE categories supported in LTE Release 10. The leftmost column includes UE categories 1-8. The next column contains the maximum number of bits of the downlink shared channel (DL-SCH) transport block received within the transmission time interval (TTI). The middle column includes the maximum number of bits of one DL-SCH transport block received in the TTI. The right column of the middle column includes the total number of bits of the soft channel. The rightmost column includes the maximum number of layers supported for spatial multiplexing in DL. Spatial multiplexing is a transmission technique in MIMO wireless communication that transmits independently and individually encoded data signals from each of multiple transmit antennas.

  UE category user equipment capability signaling is defined in the following manner. LTE Release 8/9 categories 1-5 are signaled from the user equipment to the base station via the radio resource control (RRC) protocol. The RRC protocol handles layer 3 control plane signaling between the user equipment and the UTRAN. The receiving side of the message is a base station, and the base station uses the received information. However, the user equipment is not aware of the release of the base station. Therefore, in order to be able to operate in legacy networks, the user equipment can use LTE Release 8/9 UE category (1-5) using LTE Release 8/9 part of RRC protocol and LTE Release 10 part of RRC protocol. It will report both the LTE release UE category to use (6-8). The LTE Release 10 UE category is understood by LTE Release 10 compliant base stations, but not by LTE Release 8/9 compliant base stations. Furthermore, the LTE Release 10 compliant user equipment can support the number of supported MIMO layers in the uplink (UL) and downlink (DL) as well as the number of supported component carriers. To inform the base station. This information is only understood by LTE release 10 compliant base stations.

  As an example, LTE Release 10 compliant user equipment, eg, Category 6, indicates to LTE Release 10 compliant base stations that it supports up to 4 MIMO layers in the downlink (DL). The user equipment compatible with LTE Release 10 may further provide the MIMO layer information of an information element (IE) transmitted with a category value. The information element is understood by LTE release 10 but is ignored by LTE releases 8. An LTE Release 8 compliant base station that supports 4 MIMO layers in DL identifies user equipment through LTE Release 8/9, eg, Category 4, and therefore assumes user equipment that supports only 2 layers of DL MIMO. To do.

  Since the user equipment is not aware of the release by the base station, whether it operates according to an old release, eg LTE release 8/9 category, eg category 4 or a new release, eg LTE release 10 category, eg category 6. I do not understand. This has a serious impact if the user equipment behaves differently according to the category. In this example, a cell reference signal (CRS) pattern according to four layers MIMO is detected and four layers such as a rank index greater than 2, a channel quality index (CQI) and a precoding matrix index (PMI) It may be assumed that the base station operates according to four layer MIMO in the DL in order to feed back to the base station that supports the DL MIMO operation. However, this is because the base station assumes a maximum rank of 2 when decoding the control signal according to the LTE release 8/9 category, eg, category 4 indicated by the user equipment, so that the corrupted uplink (UL) control Invite signaling. If UL data is multiplexed with UL control signaling, it may result in corrupted UL data.

  As another example, LTE Release 10 capable user equipment may support more DL MIMO layers than required by the UE category. When a user apparatus operates according to a base station that does not operate with a larger number of DL MIMO layers and a larger number of DL MIMO layers, the same problem as described above occurs.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide improved communication between a user apparatus and a base station in a communication network.

  According to a first aspect, the above object is achieved by a method in a base station that communicates with user equipment in a communication network. The base station is configured to communicate with the user equipment according to the selection of at least two user equipment categories. Based on information about the selected user equipment category, the base station determines a first maximum number of transmission layers supported by the base station. The base station communicates with the user equipment according to the determined first maximum transmission layer number and the selected user equipment category.

  According to a second aspect, the object is achieved by a method in a user equipment for communicating with a base station in a communication network. The user equipment is configured to communicate with the base station according to a selection of at least two selectable user equipment categories. Based on the information about the selected user equipment category, the user equipment determines a first maximum number of transmission layers supported by the user equipment based on the information about the selected user equipment category. The user equipment communicates with the base station according to the first maximum transmission layer number and the selected user equipment category.

  According to a third aspect, the above object is achieved by a base station that communicates with user equipment in a communication network. The base station is configured to communicate with the user equipment according to the selection of at least two user equipment categories. The base station includes a determining unit that determines a first maximum number of transmission layers supported by the base station based on information about the selected user equipment category. The base station includes a communication unit that communicates with the user equipment according to the first maximum transmission layer number and the selected user equipment category.

  According to a fourth aspect, the above object is achieved by a user equipment for communicating with a base station in a communication network. The user equipment is configured to communicate with the base station according to a selection of at least two selectable user equipment categories. The user apparatus includes a determination unit that determines a first maximum number of transmission layers supported by the user apparatus based on information about the selected user apparatus category. The user apparatus includes a communication unit that communicates with the base station according to the first maximum transmission layer number and the selected user apparatus category.

  Since the base station and the user equipment have the same understanding of the maximum number of supported DL MIMO layers, improved communication between the user equipment and the base station in the communication network is provided.

  Various embodiments provide many advantages, some of which are not the complete list shown below.

  The advantage according to the present embodiment allows a user apparatus compatible with LTE Release 10 to operate in a legacy network. According to the present embodiment, LTE Release 10-compatible user equipment having a DL MIMO layer number larger than the value required for the UE category is allowed to operate in the network.

  Another advantage according to this embodiment is that the base station and the user equipment have the same understanding of the maximum number of supported DL MIMO layers. The base station can avoid scheduling user equipment with a larger DL MIMO layer than it supports. The user equipment will not report CSI feedback that the base station does not understand. This has two advantages. First, the base station can schedule the correct number of DL MIMO layers in the DL so that the user equipment can schedule with the actual number supported by its current channel support number or its capability. It is only done. Second, if CSI feedback is multiplexed and transmitted with data on the PUWSCH, the data on the PUSCH can be decoded if the size of the CSI report is known by the base station.

  Another advantage of this embodiment is that it provides improved service area and performance in a communication network.

  A further advantage of this embodiment is that it reduces the risk of corrupted UL control signaling.

  This embodiment is not limited to the features and advantages described above. Those skilled in the art will appreciate additional features and advantages by reference to the following detailed description.

The following detailed description of the invention refers to the accompanying drawings that illustrate various embodiments.
FIG. 4 is a schematic diagram illustrating an encoded transport block and encrypted bits, eg, soft buffer size, stored by a user device. FIG. 4 is a schematic diagram illustrating bits used in a first transmission and other retransmissions obtained from a circular buffer. It is the schematic which shows arrangement | positioning of the soft buffer in the release 8 of LTE in case PDSCH transmission modes are modes other than mode 3, 4, or 8. FIG. It is the schematic which shows arrangement | positioning of the soft buffer in the release 8 of LTE in case PDSCH transmission mode is mode 3, 4 or 8. FIG. It is a figure which shows a carrier aggregation. It is the schematic which shows the communication network which concerns on this embodiment. , , , It is a flowchart which shows the method which concerns on this embodiment. It is a flowchart which shows the method of the base station which concerns on this embodiment. It is a flowchart which shows the method of the user apparatus which concerns on this embodiment. It is a block diagram which shows the base station which concerns on this embodiment. It is a block diagram which shows the user apparatus which concerns on this embodiment. It is a block diagram which shows the base station and user apparatus which concern on this embodiment.

  The foregoing and other objects, features, and advantages of this embodiment are described in more detail below the more preferred embodiments shown in the accompanying drawings. In the accompanying drawings, the same reference characters indicate the same parts in the drawings. Each drawing does not necessarily limit the scale or dimensions of a given function for the sake of clarity. What is important is to show the principle of the present invention.

  FIG. 6 shows a communication network 600 according to the present embodiment. The communication network 600 may be applied in some embodiments to one or more access technologies such as, for example, LTE, LTE Advanced, WCDMA, GSM, WiMAX, or other 3GPP radio access technologies.

  The communication network 600 includes a base station 603 that manages cells. The base station 603 may be a base station such as a NodeB, an eNodeB, or other network unit that can communicate with the user equipment 605 existing in the cell via the radio carrier 604. The base station 603 may be an LTE release 8/9 or LTE release 10 compatible base station.

  The user apparatus 605 may be any appropriate communication device or a communication device having a communication function capable of communicating with the base station via a wireless channel. For example, the user apparatus 605 may be a mobile phone, a tablet computer, a smartphone, or portable information. It is not limited to fixed devices such as terminals (PDAs), laptops, MP3 players or portable DVDs or similar content devices, digital cameras, or PCs. The PC may be connected via a mobile station (mobile station) as a termination device for broadcast or multicast media. The user device 605 may be a communication device incorporated in an electronic photo frame, heart monitoring device, intrusion monitoring device or other monitoring device, weather data monitoring system, vehicle, car or transport communication device. User equipment 605 is referred to as a UE in some drawings. The user device 605 may be an LTE release 8/9 or LTE release 10 compatible user device.

  LTE Release 8/9 user equipment 605 corresponds to UE categories 1-5. As shown in Table 1 above, the other type is user equipment 605 corresponding to UE categories 6-8. This can be referred to as an LTE release 10 compliant user equipment. In this case, the user equipment 605 always signals the two UE categories to the base station 603 regardless of the base station 603 supporting LTE release. For example, UE category 6 user equipment 605 also signals UE category 5. If base station 603 supports LTE release 8/9, base station 603 will understand that user equipment 605 corresponds to UE category 5, but user equipment 605 signals UE category 6 In some cases, an older release base station 603 will not understand the UE signaling portion and will simply discard it.

  A communication method in a communication network according to some embodiments will be described with reference to an example shown in combination of a signaling diagram and a flowchart shown in FIGS. 7a to 7d.

  FIG. 7 a shows an exemplary embodiment in which user equipment 605 corresponds to LTE release 8/9 and LTE release 10. The base station 603 corresponds to LTE 8/9. By default, the user equipment 605 is assumed to be the number that the maximum supported DL MIMO layer number is associated with the LTE Release 8/9 UE category. This is because the user equipment 605 does not know whether the base station 603 knows that the user equipment 605 supports LTE Release 8/9 and LTE Release 10. The base station 603 for LTE release 8/9 assumes the maximum number of supported DL MIMO layers, such as the required value from the LTE release 8/9 category. The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 701a>
User equipment 605 communicates to base station 603 its performance performing according to at least two different UE categories in different releases associated with LTE release 8/9 and other LTE releases 10. In addition to information about the UE category, the user equipment 605 conveys information about the maximum supported DL MIMO number in each category, for example, the first maximum transmission layer number and the second maximum transmission layer number.

  For example, the first UE category associated with LTE release 8/9 may be category 3, and the second UE category associated with LTE release 10 may be category 8. As can be seen from Table 1 described above, the maximum supported DL MIMO number for category 3 is 2, and the maximum supported DL MIMO layer number for category 6 is 8.

  User equipment 605 may be configured to have a UE performance parameter indicating the maximum number of DL MIMO layers to support. The UE performance parameter may be an explicit parameter. By default, this parameter corresponds to the maximum number of supported DL MIMO layers in the LTE Release 8/9 UE category. Using the above example, the LTE Release 8/9 UE category is category 3 and the corresponding maximum supported DL MIMO layer number is 2.

<Step 702a>
As described above, the base station 603 corresponds to LTE release 8/9 in this example, so the base station 603 determines the maximum supported DL MIMO layer number according to the LTE release 8/9 UE category.

  Base station 603 signals one or more performance parameters to user equipment 605. The UE performance parameter includes the maximum supported DL MIMO layer number determined according to LTE Release 8/9.

  For example, the base station 603 corresponds to UE category 4 and the corresponding DL MIMO layer is 2. Accordingly, the base station 603 signals 2 which is the maximum supported DL MIMO layer number to the user equipment 605.

<Step 703a>
The user equipment 605 and the base station 603 communicate according to the LTE supported 8/9 UE category up to the maximum supported DL MIMO layer number for the UE category. For example, the UE category is 5, and the maximum supported DL MIMO layer number is 4.

  FIG. 7b illustrates one embodiment where user equipment 605 supports LTE Release 8/9 and LTE Release 10. FIG. 7b differs from FIG. 7a where the base station 603 supports LTE Release 10, and FIG. 7 includes step 703b. By default, the user equipment 605 assumes that the maximum supported DL MIMO layer number is the number for the UE category associated with LTE Release 8/9. As shown in Table 1 above, if the LTE Release 8/9 UE category is 3, for example, the maximum number of supported DL MIMO layers associated is 2.

  The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 701b>
This step corresponds to step 701a in FIG. 7a.

  The user equipment 605 signals its capability to operate according to at least two different releases of different UE categories related to LTE release 8/9 or other LTE release 10 to the base station 603. In addition to information about the UE category, the user equipment 605 signals information about the maximum supported DL MIMO layer number for each category, eg, the first maximum transmission layer number and the second maximum transmission layer number.

  For example, the first UE category associated with LTE release 8/9 is category 3, and the second UE category associated with LTE release 10 is category 6. As shown in Table 1 above, the maximum number of supported DL MIMO layers in category 3 is 2, and the maximum number of supported DL MIMO layers in category 6 is 4.

  User equipment 605 may be configured to have a UE performance parameter indicating the maximum number of DL MIMO layers to support. The UE performance parameter may be an explicit parameter. As a default, the p-reader corresponds to the maximum supported DL MIMO layer number in the LTE Release 8/9 UE category. Using the example described above, the LTE Release 8/9 UE category is 3, and the corresponding maximum supported DL MIMO layer number is 2.

<Step 702b>
This step corresponds to step 702a in FIG. 7a.

  As described above, the base station 603 supports LTE release 10 UE. Base station 603 supporting LTE Release 10 operates with a maximum DL MIMO layer number greater than the number associated with each LTE Release 8/9 UE category indicated by user equipment 605 in step 701b.

  For example, the base station 603 may correspond to the UE category 8 associated with the maximum number of DL MIMO layers 8. The maximum number of DL MIMO layers in category 8 supported by the base station 603 is 8> 4 greater than the maximum number of DL MIMO layers in LTE release 10 indicated by the user equipment 605 in UE category 6. Thereafter, the base station 603 operates according to the MIMO mode exceeding the number of MIMO layers according to the user equipment 605 of the UE category 6 LTE release 10 with respect to the user equipment 605, for example, operates according to the number of DL MIMO layers 8 To signal the DL MIMO layer indicator to the user equipment 605.

<Step 703b>
When the maximum DL MIMO layer number in the UE category 8 of LTE release 10 is determined to be larger than the maximum DL MIMO layer number in the UE category 6 of LTE release 10, the user equipment 605 determines that the base station 603 in step 702b. In contrast, the rank, CQI, PMI and precoding type indicator (PTI) according to the maximum number of DL MIMO layers indicated by the base station 603 are acquired and reported. The rank determines the number of layers assuming that the user device 605 can be scheduled. PTI sets the type of PMI and CQI reported by the user equipment. PMI indicates an antenna weight assumed by the user apparatus 605 to be optimal for application to beamforming. CQI relates to the coding rate that user equipment 605 can handle. If the user equipment 605 expects to use more layers than the base station 603 thinks, the user equipment 605 may report a rank that is too high. In this case, the base station 603 will not understand the rank, and will misunderstand the information as others. If the information is based on the rank reported by user equipment 605, none of PTI, CQI and PMI will be understood.

  The base station 603 receives PTI, CQI, and PMI, and uses information for link adaptation in DL (not shown in FIG. 7b).

<Step 704b>
This step corresponds to step 703a in FIG. 7a.

  The user equipment 605 and the base station 603 communicate according to the LTE release 10 UE category and up to the maximum supported DL MIMO number in the LTE release 10 UE category.

FIG. 7 c is an example of an embodiment in which user equipment 605 supports LTE Release 8/9 and LTE Release 10. The base station 603 corresponds to LTE release 10. The difference between FIG. 7c and FIG. 7b is that the base station 603 does not signal the DL MIMO layer indicator to the user equipment 605 by operating with the number of DL MIMO layers not larger than the required value from the respective UE category. . As a default, the user equipment 605 may assume that the maximum supported DL MIMO layer number is the same as the maximum transmission layer number from the UE category according to LTE Release 8/9. For the LTE release 10 base station 603, the number of layers may be between 1 and 8, as shown in Table 1. It is the operator's choice and the base station vendor's choice of how to actually build and use. In 3GPP, only the default value of the user apparatus 605 is specified, and the base station 603 is not specified. In short, the user device 605 needs to indicate what to do “smart”. The base station 603 keeps track of things based on this. The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 701c>
This step corresponds to step 701a in FIG. 7a and 701b in FIG. 7b.

  User equipment 605 signals to base station 603 the ability to operate in accordance with at least two different UE categories of different releases associated with LTE release 8/9 or associated with LTE release 10. In addition to information about the UE category, the user equipment 605 signals information about the maximum supported DL MIMO layer number for each category, eg, the first maximum transmission layer number and the second maximum transmission layer number.

  For example, the first UE category associated with LTE release 8/9 may be category 3, and the second UE category associated with LTE release 10 may be category 8. As shown in Table 1, the maximum supported DL MIMO layer number for Category 3 is 2, and the maximum supported DL MIMO layer number for Category 6 is 8.

  In this embodiment, the base station 603 operates in the number of DL MIMO layers that are not larger than the required value from each UE category, that is, 8 categories, that is, by operating in the category 6, so that the user equipment 605 transmits the DL MIMO layer index. Is not signaled.

<Step 702c>
This step corresponds to step 703a in FIG. 7a and step 704b in FIG. 7b.

  The user apparatus 605 and the base station 603 perform communication using up to the maximum supported DL MIMO layer number in the LTE release 8/9 UE category and the LTE release 10 UE category.

  FIG. 7d is an example of an embodiment in which user equipment 605 supports LTE Release 8/9 and LTE Release 10. Base station 603 supports LTE Release 10 and operates with a number of DL MIMO layers not greater than the number associated with each UE category. Although the difference between FIG. 7d and FIG. 7c is the case where the number of DL MIMO layers is smaller than the required value from each UE category, in the example illustrated in FIG. Signal transmission to 605. The indicator includes information on the maximum number of DL MIMO layers used in the base station 603. As a default, the user equipment 605 assumes that the maximum supported DL MIMO layer number is a request value from the LTE Release 8/9 UE category.

  The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 701d>
This step corresponds to step 701a in FIG. 7a, 701b in FIG. 7b, and 701c in FIG. 7c.

  User equipment 605 signals to base station 603 the ability to operate in accordance with at least two different UE categories of different releases associated with LTE release 8/9 or associated with LTE release 10. In addition to information about UE categories, user equipment 605 signals information about the maximum number of supported DL MIMO layers for each UE category.

  For example, the first UE category associated with LTE release 8/9 may be category 3, and the second UE category associated with LTE release 10 may be category 8. As shown in Table 1, the maximum supported DL MIMO layer number for Category 3 is 2, and the maximum supported DL MIMO layer number for Category 6 is 8.

<Step 702d>
In this embodiment, the base station 603 operates with a required value from each UE category, that is, with a DL MIMO layer number of 4 which is not larger than 8. Even though the number of DL MIMO layers is smaller, the base station 603 sets the number of DL MIMO layers used by the base station 603, that is, the number of DL MIMO layers smaller than the required value from each UE category. Signal.

<Step 703d>
This step corresponds to step 703b in FIG. 7b.

  When the DL MIMO layer number is smaller than the required value, the user apparatus 605 obtains the rank, CQI, and PMI from the base station 603 according to the DL MIMO layer number indicated by the base station 603 or the required value from the UE category. To report.

<Step 704d>
This step corresponds to step 703a in FIG. 7a, step 704b in FIG. 7b, and step 702c in FIG. 7c.

  The user apparatus 605 and the base station 603 perform communication using the maximum supported DL MIMO layer number for the UE category and the LTE release 10 UE category.

  The maximum supported DL MIMO layer number indication signaling and limitation may be implemented in an appropriate manner. In one embodiment, implicit signaling is signaled to the user equipment 605 by the base station 603. For example, the indication to the user equipment 605 of the performance that operates according to the UE category of the user equipment 605 is specifically performed by either signaling to the user equipment 605 or broadcasting. In other embodiments, the user equipment 605 assumes a predetermined default value with a codebook subset restriction corresponding to the maximum number of supported DL MIMO layers in the LTE Release 8/9 UE category indicated by the user equipment 605. The codebook subset limit corresponds by default to the maximum number of DL MIMO layers supported by the LTE Release 8/9 UE category by limiting the maximum report rank from the user equipment. The base station 603 corresponding to LTE release 10 has a possibility of removing those restrictions when it is desired to operate the user equipment 605 according to the maximum supported DL MIMO layer number of LTE release 10. This achieves a high throughput of the user equipment 605.

  User equipment 605 may be configured to have an explicit parameter indicating the maximum number of DL MIMO layers that can be supported. As a default, the parameter can correspond to the maximum number of supported DL MIMO layers in the LTE Release 8/9 UE category indicated by the user equipment 605, although not limited thereto. When the LTE release 10 compatible base station 603 wants to operate the user apparatus 605 according to the maximum supported DL MIMO layer number of the LTE release 10 of the user apparatus 605, there is a possibility of setting a default value for the parameter. This achieves a high throughput of the user equipment 605.

  Hereinafter, the above-described method will be described from the viewpoint of the base station 603. FIG. 8 is a flowchart illustrating this method in the base station 603 that communicates with the user equipment 605 in the communication network 600. Base station 603 is configured to communicate with user equipment 605 according to a selection of at least two user equipment categories. The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 801>
This step corresponds to step 701a in FIG. 7a, step 701b in FIG. 7b, step 701c in FIG. 7c, and step 701d in FIG. 7d.

  In some embodiments, the base station 603 spells information about at least two user equipment categories and the maximum number of transmission layers for each user equipment category. The at least two categories may be a first user equipment category and a second user equipment category. The maximum number of transmission layers may be the first maximum transmission layer number and the second maximum transmission layer number.

  In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is LTE. Associated with release 10. In some embodiments, the selected user equipment category and the first maximum transmission layer number may be associated with LTE release 10 and the second maximum transmission layer number may be associated with LTE release 8/9.

<Step 802>
This step corresponds to step 702a in FIG. 7a, step 702b in FIG. 7b, step 702c in FIG. 7c, and step 702d in FIG. 7d.

  Based on the information about the selected user equipment category, the base station 603 determines the first maximum transmission layer number supported by the base station 603.

<Step 803>
This step corresponds to step 703b in FIG. 7b and step 703d in FIG. 7d.

  In some embodiments, the base station 603 receives channel state information according to a first maximum number of transmission layers from the user equipment 605. The channel state information includes information about the state of the radio channel 604 between the user equipment 605 and the base station 603. The channel state information may be rank, CQI, PMI, and PTI.

<Step 804>
This step corresponds to step 702a in FIG. 7a, step 702b in FIG. 7b, and step 702d in FIG. 7d.

  In some embodiments, the base station 603 transmits information about the first maximum transmission layer number to the user equipment 605. The first maximum transmission layer number is supported by the base station 603.

  In some embodiments, the first maximum transmission layer number is transmitted to the user equipment 605 when the first maximum transmission layer number is greater than the second maximum transmission layer number.

  The base station 603 may transmit information on the first maximum number of transmission layers to the user equipment 605 via a radio resource control (RRC) protocol.

<Step 805>
This corresponds to step 703a in FIG. 7a, step 704b in FIG. 7b, step 702c in FIG. 7c, and step 704d in FIG. 7d.

  The base station communicates with the user equipment 605 according to the first maximum transmission layer and the selected user equipment category.

  In some embodiments, the communication with the user equipment 605 using the first maximum number of transmission layers and the selected user equipment category is a downlink communication from the base station 603 to the user equipment 605. . In the present embodiment, such communication is referred to as DL MIMO communication.

  Hereinafter, the above-described method will be described from the viewpoint of the user device 605. FIG. 9 illustrates the method in a user equipment 605 that communicates with a base station 603 in a communication network 600. User equipment 605 is configured to communicate with base station 603 according to at least two user equipment categories. The method includes the following steps. Note that any one of the steps may be other appropriate steps than those described below.

<Step 901>
This step corresponds to step 701a in FIG. 7a, step 701c in FIG. 7c, and step 701d in FIG. 7d.

  In some embodiments, the information about the first maximum number of transmission layers is preset at user equipment 605.

  In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is LTE. Associated with Release 10 of In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with LTE release 10 and the second maximum transmission layer number is associated with LTE release 8/9.

<Step 902>
This step corresponds to step 702a in FIG. 7a, step 702b in FIG. 7b, step 702c in FIG. 7c, and step 702d in FIG. 7d.

  With information about the selected user equipment category, the user equipment 605 determines a first maximum number of transmission layers supported by the user equipment 605.

<Step 903>
This step corresponds to step 703b in FIG. 7b and step 703d in FIG. 7d.

  In some embodiments, the user equipment 605 obtains information about the state of the radio channel 604 between the user equipment 605 and the base station 603 according to the first maximum transmission layer number.

<Step 904>
This step corresponds to step 703b in FIG. 7b and step 703d in FIG. 7d.

  In some embodiments, the user equipment 605 transmits the acquired channel state information to the base station 603.

<Step 905>
This step corresponds to step 702a in FIG. 7a, step 702b in FIG. 7b, and step 702d in FIG. 7d.

  In some embodiments, the user equipment 605 receives information from the base station 603 for the first maximum transmission layer number.

  In some embodiments, the user equipment 605 receives information about the first maximum transmission layer number when the first maximum transmission layer number is greater than the second maximum transmission layer number.

  In some embodiments, information about the first maximum number of transmission layers is received 906 from the base station 603 via a radio resource control (RRC) protocol.

<Step 906>
This step corresponds to step 703a in FIG. 7a, step 704b in FIG. 7b, step 702c in FIG. 7c, and step 704d in FIG. 7d.

  The user apparatus 605 communicates with the base station 603 according to the first maximum transmission layer number and the selected user apparatus category.

  In some embodiments, the communication with the base station 603 using the first maximum number of transmission layers and the selected user equipment category is a downlink communication in the direction from the base station 603 to the user equipment 605. is there.

  In order to perform the method steps shown in FIG. 8 for communicating with the user equipment 605 in the communication network 600, the base station 603 has the configuration shown in FIG. Base station 603 is configured to communicate with user equipment 605 according to the selection of at least two categories.

  The base station 603 includes a determination unit 1001 that determines the first maximum number of transmission layers supported by the base station 603 based on information about the selected user equipment category.

  In some embodiments, the base station 603 comprises a transmission port 1003 configured to transmit information about the first maximum transmission layer number to the user equipment 605. In some embodiments, information about the determined maximum number of transmission layers is transmitted to the user equipment 605 when the first maximum number of transmission layers is greater than the second maximum number of transmission layers. In some embodiments, the transmission port 1003 is further configured to transmit information about the first maximum transmission layer number to the user equipment 605 via radio resource control (RRC). In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is LTE. Associated with Release 10 of In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with LTE release 10 and the second maximum transmission layer number is associated with LTE release 8/9.

  The base station 603 includes a communication unit 1005 configured to communicate with the user apparatus 605 in accordance with the first maximum transmission layer number and the selected user apparatus category. In some embodiments, communication with the user equipment 605 according to the first maximum number of transmission layers and the selected user equipment category is downlink communication in the direction from the base station 603 to the user equipment 605. is there.

  In some embodiments, information about at least two user equipment categories and the maximum number of transmission layers in each user equipment category is received from user equipment 605. In some embodiments, the receive port 1008 is further configured to receive channel state information according to a first maximum transmission layer number from the user equipment 605. The channel state information includes information about the state of the radio channel 604 between the user equipment 605 and the base station 603.

  In order to perform the method steps shown in FIG. 9 for communicating with the base station 603 in the communication network 600, the user equipment 605 has the configuration shown in FIG. User equipment 605 is configured to communicate with base station 603 according to the selection of at least two user equipment categories.

  In some embodiments, the user equipment 605 comprises a receiving port 1101 configured to receive information from the base station 605 for the first maximum transmission layer number. In some embodiments, the receiving port 1101 further provides the base station 603 for the first maximum transmission layer number from 03 when the first maximum transmission layer number is greater than the second maximum transmission layer number. Configured to receive the information. In some embodiments, information about the first maximum number of transmission layers is transmitted to user equipment 605 via radio resource control (RRC). In some embodiments, information about the first maximum number of transmission layers is preset at user equipment 605. In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is LTE. Associated with Release 10 of In some embodiments, the selected user equipment category and the first maximum transmission layer number are associated with LTE release 10 and the second maximum transmission layer number is associated with LTE release 8/9.

  The user device 605 includes a determining unit 1103 configured to determine a first maximum number of transmission layers supported by the user device 605 based on information about the selected user device category.

  The user equipment 605 is further configured to communicate with the base station 603 according to the first maximum transmission layer number and the selected user equipment category. In some embodiments, the communication with the base station 603 according to the first maximum number of transmission layers and according to the selected user equipment category is a downlink communication in the direction from the base station 603 to the user equipment 605. is there.

  In some embodiments, the user equipment 605 is configured to obtain information about the state of the radio channel 604 between the user equipment 605 and the base station 603 according to the first maximum transmission layer number. Is provided.

  In some embodiments, the user equipment 605 comprises a transmission port 1108 configured to transmit information about at least two user equipment categories and the maximum number of transmission layers for each user equipment category to the base station 603. In some embodiments, the transmission port 1108 is further configured to transmit channel state information to the base station 603.

  This mechanism in communication between the user apparatus 605 and the base station 603 in the communication network 600 includes the program code for executing the functions of this embodiment, the processing unit 1010 of the base station 603 shown in FIG. 10, and the user shown in FIG. Implemented through one or more processors, such as the processing unit 1120 of the device 605. The processor may be, for example, a digital signal processor (DSP), an application specific integrated circuit (ASIC) processor, a field programmable gate array, or a microprocessor. The program code described above can be provided as a computer program. For example, when the program code is loaded into at least one of the user apparatus 605 and the base station 603, a storage medium carrying the program code for executing the present embodiment is provided. May be provided in a format. However, other storage media such as a memory stick can be applied. Furthermore, the computer program code may be provided only as program code executed on a server and downloaded to at least one of the user device 605 and the base station 603 remotely.

  FIG. 12 shows an example of a base station 603 and user equipment 605 that implement the above-described technology including a signaling function. Base station 603 comprises a central base station controller 1201 connected to one or more memories 1203 that perform soft buffering. In connection with user equipment 605, soft buffering may be referred to to perform rate matching according to the total amount of soft channel bits. In connection with the base station 603, soft buffering may be referred to to perform rate matching according to the total amount of soft channel bits. The radio frequency (RF) circuit 1205 is connected to a plurality of antennas 1208 that perform radio transmission and reception with respect to the base station. In FIG. 12, four antennas 1208 are shown as an example. The antenna 1208 in FIG. 12 corresponds to the transmission port 1003 and the reception port 1009 in FIG. The example of FIG. 12 shows that carrier aggregation is supported. A plurality of processors corresponding to the determination unit 1001, the processing unit 1010, and the communication unit 1005 in FIG. 10 execute corresponding tasks including the HARQ processor 1210, the UE category signaling processor 1212, and the MIMO layer processor 1215.

  The user device 605 comprises similar processing units and memory blocks according to its release, more or less elaborate, bandwidth and other functions. User device 605 comprises a central user device controller 1220 connected to one or more memories 1223 that perform soft buffering. The RF circuit 1225 is connected to a plurality of antennas 1228 for performing wireless transmission / reception with respect to the user apparatus 605. In FIG. 12, two antennas 1228 are shown as an example. The antenna 1228 in FIG. 12 corresponds to the transmission port 1108 and the reception port 1101 in FIG. The plurality of processors corresponding to the determination unit 1103, the processing unit 1120, the acquisition unit 1109, and the communication unit 1105 execute corresponding tasks including the HARQ processor 1230, the UE category signaling processor 1232, and the MIMO layer processor 1235. The user device 605 further includes a user interface 1240 for enabling interaction with the user of the user device 605.

  Although detailed descriptions of specific embodiments and the like have been described, they are for purposes of illustration and are not intended to be limiting. However, it will be understood by one of ordinary skill in the art that other embodiments may be employed apart from their specific details. In some instances, detailed descriptions of known methods, nodes, interfaces, circuits, and devices are omitted so as not to obscure the unnecessary detail. Those skilled in the art will understand that the functions described above are hardware circuits such as analog and / or discrete logic gates that use software programs and data in conjunction with one or more digital microprocessors or general purpose computers. It will be appreciated that it may be implemented at one or more nodes using logic gates interconnected to perform dedicated functions, ASICs, PLAs, etc. Nodes that communicate using the air interface also include suitable wireless communication circuitry. In addition, the present invention is additionally implemented in the form of a computer readable memory such as a semiconductor memory, magnetic disk, or optical disk that includes an appropriate set of computer instructions that cause a processor to perform the above control. Can be considered.

  Hardware implementations include, but are not limited to, digital signal processor (DSP) hardware, reduced instruction set processors, hardware such as digital or analog, but not limited to application specific integrated circuits (ASIC) and field programmable gates A circuit including at least one of an array (FPGA) and a suitable state machine capable of performing the functions as described above may be included or included.

  In computer-implemented terminology, a computer is generally understood to comprise one or more processors or one or more controllers, a term computer, a processor, and a controller used interchangeably. If provided by a computer, processor, or controller, the functions may be shared by a single dedicated computer, processor or controller, by a single shared computer, processor or controller, or some may be shared or distributed. A plurality of individual computers, processors or controllers. Further, the term “processor” or “controller” may also be referred to as other hardware capable of performing the functions as described above or executing software, such as the hardware described above.

  Although the description has been given above, the present invention is not limited to the above-described exemplary contents.

  Although the above description includes many specific details, it is intended to provide a description of some preferred embodiments and should not be construed as limiting. The present invention may well include other embodiments as will be apparent to those skilled in the art. An element recited in the singular is not intended to mean “one and only” but rather to mean “one or more” unless explicitly stated otherwise. All configurations and feature equivalents known to those skilled in the art of the elements of the above-described embodiments are expressly included in the description of this specification and are intended to be included in the present disclosure. Further, there is no need for an apparatus or method that solves each and every problem that is sought to be solved by the matters that can be disclosed herein.

Claims (30)

A method in a base station (603) for communicating with a user equipment (605) according to a selection of at least two user equipment categories in a communication network (600) comprising:
Determining (702a, 702b, 702c, 702d, 802) a first maximum number of transmission layers supported by the base station (603) based on information about the selected user equipment category;
Transmitting (702a, 702b, 702d, 804) an indicator of the first maximum transmission layer number to the user equipment (605);
Communicating with the user equipment (605) according to the determined first maximum number of transmission layers and according to the selected user equipment category (703a, 704b, 702c, 704d, 805). Feature method. Receiving (701a, 701b, 701c, 701d, 801) information about the at least two user equipment categories and the indicator of the maximum number of transmission layers in each user equipment category from the user equipment (605); The method of claim 1, comprising: The indicator of the first maximum transmission layer number is transmitted to the user apparatus (605) when the first maximum transmission layer number is larger than the second maximum transmission layer number. The method of claim 2 . Channel state information according to the first maximum number of transmission layers, including information about a state of a radio channel (604) between the user apparatus (605) and the base station (603), is transmitted to the user apparatus (605). The method according to claim 3 , further comprising the step of receiving from (703b, 703d, 803). The index of the first maximum number of transmission layers is transmitted to the user equipment (605) via a radio resource control (RRC) protocol (702a, 702b, 702d, 804). 5. The method according to any one of 1 to 4 . The step (703a, 704b, 702c, 704d, 805) of communicating with the user equipment (605) according to the determined first maximum number of transmission layers and according to the selected user equipment category is the base the method according to any one of claims 1 to 5, characterized in that the station (603) a downlink communication in the direction of the user device (605). The selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is associated with LTE Release 10 Or
The selected user equipment category and the first maximum transmission layer number are associated with LTE release 10, and the second maximum transmission layer number is associated with LTE release 8/9. 7. A method according to any one of claims 1-6 . A method in a user equipment (605) for communicating with a base station (603) according to a selection of at least two user equipment categories in a communication network (600) comprising:
Determining (702a, 702b, 702c, 702d, 902) a first maximum number of transmission layers supported by the user equipment (605) based on information about the selected user equipment category;
Receiving (702a, 702b, 702d, 905) an indicator of the first maximum transmission layer number from the base station (603);
Communicating (703a, 704b, 702c, 704d, 906) with the base station (603) according to the first maximum number of transmission layers and according to the selected user equipment category. Method. Further comprising transmitting (701a, 701c, 701d, 901) information about at least two user equipment categories and the indicator of the maximum number of transmission layers in each user equipment category to the base station (603). 9. A method according to claim 8 , characterized in that The indicator of the first maximum transmission layer number is received from the base station (603) when the first maximum transmission layer number is larger than the second maximum transmission layer number (702a, 702b, 702d, 905) the method according to claim 9, characterized in that. Acquiring channel state information about the state according to the first maximum number of transmission layers, which is a state of a radio channel (604) between the user equipment (605) and the base station (603) (703b, 703d, 903),
11. The method according to any one of claims 8 to 10 , further comprising the step (703b, 703d, 904) of transmitting the channel state information to the base station (603). The indicator of the first maximum number of transmission layers is received from the base station (603) via a radio resource control (RRC) protocol (702a, 702b, 702d, 905). The method according to any one of 8 to 11 . The step ( 703a, 704b, 702c, 704d, 906 ) of communicating with the base station (603) according to the first maximum number of transmission layers and according to the selected user equipment category is the base station (603 13. The method according to any one of claims 8 to 12 , characterized in that the communication is a downlink communication in the direction from the user equipment (605). The method according to one of claims 8 to 13 , wherein the indicator of the first maximum number of transmission layers is preset in the user equipment (605). The selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is associated with LTE Release 10 Or
The selected user equipment category and the first maximum transmission layer number are associated with LTE release 10, and the second maximum transmission layer number is associated with LTE release 8/9. 15. A method according to any one of claims 8 to 14 . A base station (603) communicating with a user equipment (605) according to a selection of at least two user equipment categories in a communication network (600),
A determination unit (1001) for determining a first maximum number of transmission layers supported by the base station (603) based on information about the selected user equipment category;
A transmission port (1003) for transmitting the indicator of the first maximum transmission layer number to the user apparatus (605);
A base station (603) comprising: a communication unit (1005) that communicates with the user equipment (605) according to the first maximum number of transmission layers and the selected user equipment category. The receiver port (1008) further receiving information about the at least two user device categories and the indicator of the maximum number of transmission layers in each user device category from the user device (605). Item 16. The base station (603) according to item 16 . The indicator of the first maximum transmission layer number is transmitted to the user apparatus (605) when the first maximum transmission layer number is larger than the second maximum transmission layer number. The base station (603) according to claim 17 . The receiving port (1008) further according to the first maximum number of transmission layers including information about a state of a radio channel (604) between the user equipment (605) and the base station (603) The base station (603) according to claim 17 or 18 , characterized in that channel state information is received from the user equipment (605). The transmission port (1003) further transmits the indicator of the first maximum transmission layer number to the user equipment (605) via a radio resource control (RRC) protocol. The base station (603) according to any one of 16 to 19 . Communication with the user equipment (605) according to the determined first maximum number of transmission layers and the selected user equipment category is performed from the base station (603) to the user equipment (605). 21. Base station (603) according to any one of claims 16 to 20 , characterized in downlink communication in the direction to. The selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is associated with LTE Release 10 Or
The selected user equipment category and the first maximum transmission layer number are associated with LTE release 10, and the second maximum transmission layer number is associated with LTE release 8/9. The base station (603) according to any one of claims 16 to 21 . A user equipment (605) communicating with a base station (603) according to a selection of at least two user equipment categories in a communication network (600),
A determination unit (1103) for determining a first maximum number of transmission layers supported by the user device (605) based on information about the selected user device category;
A reception port (1101) for receiving an indication of the first maximum transmission layer number from the base station (603);
A user apparatus (605) comprising a communication unit (1105) that communicates with the base station (603) according to the first maximum transmission layer number and the selected user apparatus category. The transmission port (1108) for transmitting information about at least two user equipment categories and the indicator of the maximum number of transmission layers in each user equipment category to the base station (603). The user device (605) according to 23 . The receiving port (1101) further includes:
The index of the first maximum transmission layer number is received from the base station (603) when the first maximum transmission layer number is larger than a second maximum transmission layer number. Item 24. A user device (605) according to item 24 . Acquisition of channel state information for the state according to the first maximum number of transmission layers, the state of the radio channel (604) between the user equipment (605) and the base station (603) Part (1109),
The user equipment (605) according to any one of claims 23 to 25 , further comprising a transmission port (1108) for transmitting the channel state information to the base station (603). The indicator of the first maximum number of transmission layers is received from the base station (603) via a radio resource control (RRC) protocol (702a, 702b, 702d, 906). The user device (605) according to any one of 23 to 26 . Communication (703a, 704b, 702c, 704d, 907) with the base station (603) according to the first maximum transmission layer number and the selected user equipment category is performed by the base station (603 28 ) User device (605) according to any one of claims 23 to 27 , characterized in that it is a downlink communication in the direction from the user device (605) to the user device (605). 29. The user equipment (605) according to any one of claims 23 to 28 , wherein the indicator of the first maximum number of transmission layers is preset in the user equipment (605). The selected user equipment category and the first maximum transmission layer number are associated with Long Term Evolution (LTE) Release 8/9, and the second maximum transmission layer number is associated with LTE Release 10 Or
The selected user equipment category and the first maximum transmission layer number are associated with LTE release 10, and the second maximum transmission layer number is associated with LTE release 8/9. 30. A user device (605) according to any one of claims 23 to 29 .

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